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Over Heating
- Thread starter howehap
- Start date
RootesRooter
Donation Time
It's that your Alpine consistently shoots up to 205 under ALL driving conditions (idling, cruising, high speed) that' s most interesting. A blown head gasket should explain it, but its apparently intact. Even a partially blocked radiator should keep the engine cooler if you're cruising at 40mph. Best guess is that either the numbers are off, several rows in the radiator are blocked, or you've got a ton of silt built up in the back of the block.
Other long shots:
Last winter you put a piece of cardboard in front of the radiator to keep ii warm - and forgot about it.
A long time ago there was a rumored batch of water pumps with plastic impellers that were said to be prone to slipping on the shaft, leading to overheating. But that was usually a high-speed phenomenon.
Wrong (cast iron?) head gasket - water jacket holes don't line up.
Finally, does popping the hood while driving lower the temp at all? For my SV, it's usually good for 5-10 degrees on hot days at freeway speeds.
I also might suggest going to a radiator shop and getting a proper cooling system pressure test done to make sure you don't have a very slow leak.
Other long shots:
Last winter you put a piece of cardboard in front of the radiator to keep ii warm - and forgot about it.
A long time ago there was a rumored batch of water pumps with plastic impellers that were said to be prone to slipping on the shaft, leading to overheating. But that was usually a high-speed phenomenon.
Wrong (cast iron?) head gasket - water jacket holes don't line up.
Finally, does popping the hood while driving lower the temp at all? For my SV, it's usually good for 5-10 degrees on hot days at freeway speeds.
I also might suggest going to a radiator shop and getting a proper cooling system pressure test done to make sure you don't have a very slow leak.
Last edited:
howehap
Platinum Level Sponsor
Bill,
Here is the temp data in one place:
Here is the temp data in one place:
- Outside ambient 85F, engine idling 1000 rpm
- Thermostat housing 205F.
- Top radiator header 205F
- Radiator fin temp ~185 around outside of the fan flow area, near edges of the radiator core (measured by pointing gun at radiator core from front of car)
- Radiator fin temp ~ 175 in front of core that is directly in line with fan
- Bottom radiator header ~200 F (measured along bottom of header and where bottom hose is attached.
I'd say your problem is a coated radiator not allowing heat to transfer to the fins. How else could you have cool fins and hot water? I suppose it is possible to "boil out" the radiator and remove whatever is coating it, but you'd probably be better off with a new radiator or re-core the old one. EPA regulations enacted 25 years ago effectively eliminated boil outs. The tanks and process are still legal, but the chemicals (acid) used int the process puts the shop under heavy local regulation. A reverse flush with air is about all any shop will do. If you have another radiator, try swapping.
Bill
Bill
howehap
Platinum Level Sponsor
Bill,
This makes sense to me from physics / heat transfer . Before I do it I'm going to try the measure the fin temp and header temp on my truck for comparision. I'm not sure what temperature the gun is picking up when I point it at the fins. Is the gun picking up fins, tubes, openings in radiator between fins, average radiation temp of everything? I will report back on the science experiment. I tried different angles, but the temperature was about the same.
I guess I plan on replacing radiator with one from my series 4 that has not run since I got it in 1976. I will look at inside of hoses, thermostat direction (I'm sure it's right), etc.
This makes sense to me from physics / heat transfer . Before I do it I'm going to try the measure the fin temp and header temp on my truck for comparision. I'm not sure what temperature the gun is picking up when I point it at the fins. Is the gun picking up fins, tubes, openings in radiator between fins, average radiation temp of everything? I will report back on the science experiment. I tried different angles, but the temperature was about the same.
I guess I plan on replacing radiator with one from my series 4 that has not run since I got it in 1976. I will look at inside of hoses, thermostat direction (I'm sure it's right), etc.
howehap
Platinum Level Sponsor
Results of science experiment 2004 GMC 4.8 L V8. Temp gage ~200F
- Radiator inlet hose and inlet header ~170F
- Radiator outlet hose and outlet header ~140F
- fins on radiator~155F (ac condenser is in front of radiator, so I had to turn off engine and quickly shoot between fan blades on backside of radiator